Created attachment 120893 DP debugging Tom, I would bother you again to provide some debugging info. From the dmesg you sent it seems that you are experiencing a lot of hpd interrupts. When that happens the driver checks if the DP channel equalization is still ok. On your case, channel equalization is not ok yielding DP link to be retrained. Of course, this causes flickering as the DP link is broken for some time. The patch I'm proposing for debugging purposes applies on top of the latest -nightly and on top of these previous patches
https://patchwork.freedesktop.org/patch/69394/ https://patchwork.freedesktop.org/patch/69395/ https://patchwork.freedesktop.org/patch/69396/ The patch adds more verbose debug information on channel equalization and limits the DP link retraining to 5. After 5 attempts to retrain the link you probably end up having a non-flickering display or a black screen. Please, report back with dmesg. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to libdrm in Ubuntu. https://bugs.launchpad.net/bugs/1522922 Title: Screen flickering in Intel i915 driver Status in Nouveau Xorg driver: Incomplete Status in libdrm package in Ubuntu: Confirmed Bug description: There's an upstream bug reported here https://bugs.freedesktop.org/show_bug.cgi?id=91393 that causes screen flickering when using the Intel i915 builtin driver (at resolutions lower than the maximal one). I think that it will be fixed in newer kernel versions, but for the time being, as reported here https://bugs.freedesktop.org/show_bug.cgi?id=91393#c25 (and as personally tested) reverting those two commits fixes the problem. Would that be possible to release a fixed version for the 4.2.0 stream? ProblemType: Bug DistroRelease: Ubuntu 15.10 Package: linux-image-4.2.0-19-generic 4.2.0-19.23 ProcVersionSignature: Ubuntu 4.2.0-19.23-generic 4.2.6 Uname: Linux 4.2.0-19-generic x86_64 ApportVersion: 2.19.1-0ubuntu5 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: bettini 1378 F.... pulseaudio /dev/snd/controlC1: bettini 1378 F.... pulseaudio CurrentDesktop: KDE Date: Fri Dec 4 19:01:00 2015 HibernationDevice: RESUME=UUID=7ddbc972-3ad6-40de-9313-2bb9395145f9 InstallationDate: Installed on 2015-05-08 (210 days ago) InstallationMedia: Kubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422) MachineType: Dell Inc. Dell Precision M3800 ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-19-generic root=UUID=dd2c7064-53b9-4720-96ab-5e8a3f2db3ea ro noprompt quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-4.2.0-19-generic N/A linux-backports-modules-4.2.0-19-generic N/A linux-firmware 1.149.3 SourcePackage: linux UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev' UpgradeStatus: Upgraded to wily on 2015-11-07 (26 days ago) dmi.bios.date: 08/17/2015 dmi.bios.vendor: Dell Inc. dmi.bios.version: A10 dmi.board.name: Dell Precision M3800 dmi.board.vendor: Dell Inc. dmi.board.version: A10 dmi.chassis.type: 8 dmi.chassis.vendor: Dell Inc. dmi.chassis.version: Not Specified dmi.modalias: dmi:bvnDellInc.:bvrA10:bd08/17/2015:svnDellInc.:pnDellPrecisionM3800:pvrA10:rvnDellInc.:rnDellPrecisionM3800:rvrA10:cvnDellInc.:ct8:cvrNotSpecified: dmi.product.name: Dell Precision M3800 dmi.product.version: A10 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/nouveau/+bug/1522922/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp